fix: avoid line breaks between class members head and key (#12653)

packages/babel-generator/src/generators/classes.js

@@ -71,6 +71,11 @@ export function ClassBody(node: Object) {
 
 export function ClassProperty(node: Object) {
   this.printJoin(node.decorators, node);
+
+  // catch up to property key, avoid line break
+  // between member modifiers and the property key.
+  this.source("end", node.key.loc);
+
   this.tsPrintClassMemberModifiers(node, /* isField */ true);
 
   if (node.computed) {
@@ -131,6 +136,9 @@ export function ClassPrivateMethod(node: Object) {
 
 export function _classMethodHead(node) {
   this.printJoin(node.decorators, node);
+  // catch up to method key, avoid line break
+  // between member modifiers/method heads and the method key.
+  this.source("end", node.key.loc);
   this.tsPrintClassMemberModifiers(node, /* isField */ false);
   this._methodHead(node);
 }

packages/babel-generator/test/fixtures/decorators-legacy/ts-class-modifier-with-retainlines/input.js

@@ -0,0 +1,23 @@
+class A {
+  @decorate
+  public p = "p"
+
+  @decorate
+  public m() {}
+
+  @decorate
+  private set s
+  (v) {}
+
+  @decorate
+  public [
+    cp
+  ]
+  = "cp"
+
+  @decorate
+  private [
+    cm
+  ]
+  () {}
+}

packages/babel-generator/test/fixtures/decorators-legacy/ts-class-modifier-with-retainlines/options.json

@@ -0,0 +1 @@
+{ "plugins": ["classProperties", "decorators-legacy", "typescript"], "decoratorsBeforeExport": true, "retainLines": true }

packages/babel-generator/test/fixtures/decorators-legacy/ts-class-modifier-with-retainlines/output.js

@@ -0,0 +1,22 @@
+class A {
+  @decorate
+  public p = "p";
+
+  @decorate
+  public m() {}
+
+  @decorate
+  private set s(
+  v) {}
+
+  @decorate
+
+  public [cp] =
+
+  "cp";
+
+  @decorate
+
+  private [cm]()
+
+  {}}

packages/babel-generator/test/fixtures/decorators/accessor-with-retainlines/input.js

@@ -0,0 +1,7 @@
+class C {
+  @dec
+  get a() {}
+
+  @dec
+  set a(v) {}
+}

packages/babel-generator/test/fixtures/decorators/accessor-with-retainlines/output.js

@@ -0,0 +1,8 @@
+class C {
+  @dec
+  get a() {}
+
+  @dec
+  set a(v) {}
+
+}

packages/babel-generator/test/fixtures/decorators/async-method-with-retainlines/input.js

@@ -0,0 +1,9 @@
+class C {
+  @dec
+  async a() {}
+
+  @dec
+  async *
+  a(v) {}
+
+}

packages/babel-generator/test/fixtures/decorators/async-method-with-retainlines/output.js

@@ -0,0 +1,8 @@
+class C {
+  @dec
+  async a() {}
+
+  @dec
+  async *a(v) {}
+
+}